are 36lb injectors enough?
are 36lb injectors enough? i have a 1999 camaro with delphi 36lb injectors and the motor has a FAST/NW 90mm, f14 cam, ported heads, pulley, fipk, QTP headers, ewp, and all the rest of the bolt ons. i also have the ZEX direct port that i have not used yet but my question is are the delphi 36lb injectors big enough to handle the motor and a 150 shot of nitrous?
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Injector size =
Expected hp of combination including dry nitrous
HP x 1.15 * .55
Divide by 8
Pick an injector close to your answer.
No, 36# would not be adequate.
Reasoning:
Expected HP total - 600 or so.
600 * 1.15 - 1.15 is a 15% safety margin = 690
690 *.55 - .55 is a guesstimate of your brake specific fuel consumption. This is another bit of a fudge factor but most nitrous systems are calibrated fairly rich. BSFC is how much fuel is used to make 1 horsepower in your engine for 1 hour. Its in pounds per hour like your injectors.
690 * .55 = 380
380 / 8 = 48
50# injectors would work nicely and have a bit of room to grow.
The 15% margin will ensure your injectors aren't driven static.
Expected hp of combination including dry nitrous
HP x 1.15 * .55
Divide by 8
Pick an injector close to your answer.
No, 36# would not be adequate.
Reasoning:
Expected HP total - 600 or so.
600 * 1.15 - 1.15 is a 15% safety margin = 690
690 *.55 - .55 is a guesstimate of your brake specific fuel consumption. This is another bit of a fudge factor but most nitrous systems are calibrated fairly rich. BSFC is how much fuel is used to make 1 horsepower in your engine for 1 hour. Its in pounds per hour like your injectors.
690 * .55 = 380
380 / 8 = 48
50# injectors would work nicely and have a bit of room to grow.
The 15% margin will ensure your injectors aren't driven static.
According to those calculations, the stock injectors aren't even big enough for a stock car.
350 HP x 1.15 * .55 = 221.375
221.375 / 8 = 27.671875
I guess the LS1s that came with 26 lb injectors are maxing out their injectors?
350 HP x 1.15 * .55 = 221.375
221.375 / 8 = 27.671875
I guess the LS1s that came with 26 lb injectors are maxing out their injectors?
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Originally Posted by PAGregSS
According to those calculations, the stock injectors aren't even big enough for a stock car.
350 HP x 1.15 * .55 = 221.375
221.375 / 8 = 27.671875
I guess the LS1s that came with 26 lb injectors are maxing out their injectors?
350 HP x 1.15 * .55 = 221.375
221.375 / 8 = 27.671875
I guess the LS1s that came with 26 lb injectors are maxing out their injectors?
I'm not aware of an LS1 F-body with nitrous or forced induction from the factory. Either of those increase the BSFC of the engine. In other words it takes or uses more fuel to make power. So the injector size is factored on the larger side due to the higher fuel consumption.
I tried to point that out in my post.
Touche! I'll apply that logic then. I, as well as many others, must be running the stock injectors at over 100% duty cycle using a NOS 5177 dry kit on a stock car. By adding nitrous, per your logic, I was increasing the BSFC of the engine by adding the nitrous. Since my calculations above show that the injectors were already too small to handle the demands of the stock motor, when nitrous was added, the injectors must be running at 200% duty cycle.
Not trying to argue here, I was actually using the equation to figure out what injectors I would need and discovered the above results. I just found it a little odd.
Not trying to argue here, I was actually using the equation to figure out what injectors I would need and discovered the above results. I just found it a little odd.
I am trying to figure the same thing out about that as well. I am running prc ls6 heads milled.030 and a tr224 cam. I am hoping over 400rwhp through an automatic. I am putting in fast 36lb injectors. According to the calculations above they are too small. Are my calculations right. The reason I ask is when I was running a much bigger cam hptuners said my injector duty cycle was 99%.
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Launching!
Joined: Jan 2003
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From: Saginaw, MI
Similar question on setups. For the sack of arqument lets say the stock fuel pump can handle 450rwhp. (atleast for a short wot) Using around a 100 shot of nitrous I get to the magic 450 mark. What Injectors?? Do I really care if the duty cycle is 90-95 for a few seconds?
What size is the 500hp Zo6 inj.???????
What size is the 500hp Zo6 inj.???????
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Originally Posted by RedWS6 00
Dont forget some injectors or probably most have their flow ratings at 43 PSI, the LS1 fuel pressure is 58 PSI, therefore a 36lb/hr @ 43 PSI will flow about 48lb/hr.
(((NewPressure/RatedPressure)SQRT)*injectorflow@RatedPressure)=Ne wFlow
58/43=1.348
SQRT of 1.348 = 1.161
1.161 * 36 = 41.81 lbs/hr
To confuse matters more some injectors from Ford are rated at 39 psi.
if you sprang for direct port - why didn't you go with a wet kit?
not sure about your kit, but you could just convert it over to a wetkit without too much trouble and that would take care of the problem. Just make sure your fuel pump, etc are up to snuff.
not sure about your kit, but you could just convert it over to a wetkit without too much trouble and that would take care of the problem. Just make sure your fuel pump, etc are up to snuff.
Originally Posted by PAGregSS
I, as well as many others, must be running the stock injectors at over 100% duty cycle using a NOS 5177 dry kit on a stock car. By adding nitrous, per your logic, I was increasing the BSFC of the engine by adding the nitrous.
Dyno for the 50 shot was @ 341 HP/355 Torque
With a 125 wet shot @ 5900 RPM my injectors are running 81% DC
Last edited by Beer99C5; Aug 26, 2006 at 08:55 PM.
